This invention relates generally to trocar systems including cannulas and, more specifically, to trocars having a cannula stabilization seal.
Trocar systems have been of particular advantage in facilitating less invasive surgery across a body wall and within a body cavity. This is particularly true in abdominal surgery where trocars have provided a working channel across the abdominal wall to facilitate the use of instruments within the abdominal cavity.
Trocar systems typically include a cannula, which provides the working channel, and an obturator that is used to place the cannula across a body wall, such as the abdominal wall. The obturator is inserted into the working channel of the cannula and pushed through the body wall with a penetration force of sufficient magnitude to result in penetration of the body wall. Once the cannula has traversed the body wall, the obturator can be removed.
With the cannula in place in the body wall, various instruments may be inserted through the cannula into the body cavity. One or more cannulas may be used during a procedure. During the procedure, the surgeon manipulates the instruments in the cannulas, sometimes using more than one instrument at a time. The manipulation of an instrument by a surgeon may cause frictional forces between the instrument and the cannula in which the instrument is inserted. These frictional forces may result in movement of the cannula in an inward or outward direction within the body wall. If the cannula is not fixed in place, there is a potential that proximal or distal motions of the instruments through the cannula may cause the cannula to slip out of the body wall or to protrude further into the body cavity, possibly leading to injury to the patient.
The surfaces of the cannula associated with a trocar are generally smooth. The smoothness of a cannula surface makes placement of the cannula through a body wall relatively easy and safe. However, a smooth cannula may not have desired retention characteristics once the cannula has been placed through a body wall. This may present problems as instruments and specimens are removed from a body cavity through the cannula and the associated seal systems of the trocar. It is highly desirable for a cannula to remain fixed in the most appropriate position once placed.
Many solutions to the issue of trocar-cannula fixation or stabilization have been formed. These include an inflatable balloon attached to the distal portion of a cannula, raised threads or rings associated with the outer surface of the cannula, mechanically deployable enlarging portions arranged at the distal end of a cannula and suture loops or hooks associated with the proximal end of the trocar. These solutions have provided some degree of fixation or stabilization. However, there remains a need for a fixation or stabilization device that may be used with a variety of trocar-cannulas and addresses the additional requirements associated with developing laparoscopic surgical procedures and techniques. More particularly, the cannula must provide retention means to prevent the cannula from slipping out of the body cavity and provide sufficient sealing force to provide a gas-tight seal against adjacent tissue in the body wall.